Development of a GaAs avalanche electron-emitting diode cold-electron emitter

In an avalanche electron-emitting diode (AEED), the electrons are emitted after being accelerated in the internal electric field of a very shallow p-n junction biased in avalanche breakdown. Silicon cold cathodes based on this principle have been shown to have a very high reduced brightness on the order of 1000 A/(cm² sr V) and have emission-to-junction current efficiencies on the order of a few percent. Triggered by the results obtained on these silicon cold cathodes, a research project on this subject was started at the Delft University of Technology. Its aim is to investigate whether a semiconductor other than silicon would be even better. Work was started on gallium arsenide. The main reason for choosing GaAs is the existing information on technological possibilities and physical properties. In order to obtain a direct comparison between silicon and gallium arsenide, the geometrical design of the silicon AEED is mimicked as well as possible. The process steps involved in making the devices from molecular-beam-epitaxy-grown substrates can also be used for different materials. The devices have been tested in air for their electrical properties, and vacuum tests are in progress. Removal of the surface oxides is planned by sputtering low-energy (100-200 eV) inert gas atoms or ions.